It has been conventionally known that a pressure-sensitive adhesive sheet including a pressure-sensitive adhesive layer that is formed from a pressure-sensitive adhesive composition is attached (applied) to an object to be attached (applied) such as a wall or a roof material and then, a moisture-permeable waterproof sheet is attached thereto from the upper side thereof.
As the pressure-sensitive adhesive composition that forms the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet, for example, a pressure-sensitive adhesive composition that is prepared by kneading 1000 g of a reclaimed butyl rubber and 500 g of a polybutene having a kinetic viscosity at 40° C. of 26000 mm2/s has been proposed (ref: for example, the following Patent Document 1).